This invention relates to a heavy duty automotive air cleaner for use in operating environments with high contaminant concentrations.
A common heavy duty air cleaner design for use in environments with high contaminant concentrations typically provides a centrifugal separator in series with a filter cartridge containing, typically, a pleated paper medium. Such a prior art air cleaner design is disclosed in U.S. Pat. No. 3,508,383. In air cleaners of this type, entering air is subjected to the centrifugal separator so that the heavier particles are centrifuged radially outwardly with respect to the air cleaner housing and therefore drop from the flow stream. The flow stream then communicates to the pleated paper medium in the filter element, where most of the remaining particles are removed. One problem associated with air cleaners of this type is their relatively limited capacity, and the fact that they are relatively inefficient in removing smaller particulate matter.
The present invention solves the problems inherent in the prior art heavy duty air filter designs by providing a pair of flow paths which extend through the filter housing between the inlet and outlet. One of the flow paths extends through a centrifugal vane-type separator. Although only some of the air is communicated through the separator, the spiral flow-inducing effects of the separator are also felt upstream of the turning vanes themselves, and accordingly knock out heavier particles from all, or almost all, or the air entering the air cleaner. The air flow communicated through the centrifugal separator then communicates through a pleated paper filtering medium. The other flow path extends through a depth-type, fibrous filtering medium which is located upstream of the turning vanes and which is adapted to remove finer particulate matter from the entering air stream. The air flow communicated through the depth-type medium then communicates through the pleated paper medium. Since the depth-type medium will plug gradually until the differential required to draw air through the depth-type medium is equal to that necessary to draw air through the centrifugal separator, at which time the loaded depth-type or fibrous filter medium will become almost imperforate, and thereafter all of the flow communicates through the centrifugal separator. However, the entire pleated paper element is utilized, even that portion of the pleated paper element in series with the depth-type medium after the medium plugs, because the air communicates at relatively low velocity between the pleats of the pleated paper medium, thus assuring loading of the entire pleated paper medium.